Zenapax (daclizumab)

Administered via intravenous infusion every four weeks; also studied in subcutaneous injections.

Zenapax is a genetically engineered antibody against a substance necessary for the growth of T cells. It results in a sustained but reversible reduction in activated T cells, and reduces inflammation.

A study in RRMS and SPMS patients (who continued to experience worsening disease activity with interferon-beta therapy) showed the drug was well tolerated. The study also reported to improve or stabilize 60 percent of patients and reduced the number of active lesions.

The ongoing CHOICE Phase II trial adds Zenapax to interferons in 30 patients with active MS; the treated group experienced a significant reduction in new or enlarged enhancing lesions. A recent study used the drug alone in those participants in the CHOICE study who had developed neutralizing antibodies to interferon-beta. The results suggest that the effect of Zenapax is not dependent on the presence of functioning interferon-beta, indicating that it may have potential as an independent therapy.

An ongoing study of RRMS will determine the effect of three different doses of Zenapax on brain-lesion activity as measured by MRI. An extension study is also underway that will focus on safety and tolerability.